Alternating-current-motor controller.



W. E. DATE.

ALTERNATING CURRENT MOTOR CONTROLLER.

APPLIUATION FILED NOV. 2, 190B.

Patented Dec. 8, 1914.

3 SHEETS-SHEET 1.

Witnesses W.'E. DATE. ALTERNATING CURRENT MOTOR CONTROLLER.

- APPLIOATION FILED NOV. 2, 1908. 1,120,376.

Patented Dec. 8, 1914.

3 SHEETS-SHEET 2.

WHRQSSES 7% YHE NORRIS PETERS 60.. PHUT'O-LITHO., WASHINGTON. Dv C- I W.E. DATE.

ALTERNATING CURRENT MOTOR CONTROLLER.

APPLICATION FILED NOV. 2, 190a.

1. 120 37 Patented Dec. 8, 1914.

3 SHEETS-SHEET 3.

I mm THE NORRIS PETERS C0 PHOTOJJTHQ, WA 1JN0|-)N. D. c.

nnrrnn srnrns PATENT ornron.

WILLIAM E. DATE, OF VJESTFIEL'D, NEE? JERSEY, ASSIGNOR TO THECUTLER-HAMMER MFG. 60., 0F MILWAUKEE, IVISCUIQSIN, A CORPORATION OFIVISCONSIN.

ALTERNATIITG-CURRENT-MOTOR CONTROLLER.

Application filed November 2, 1908.

Z 0 aZZ whom it may concern Be it known that I, WiLLIAM E. DATE, acitizen of the United States, residing at I'Vestfield, in the county ofUnion and State of New Jersey, have invented new and useful Improvementsin Alternating-Current- Motor Controllers, of which the following is afull, clear, concise, and exact description, reference being had to theaccompanying drawing, forming a part of this specification.

My invention relates to improvements in alternating current motorstarters.

In order to secure the maximum torque for a given current in aninduction motor, the current in the three phases of the secondarywinding mustbe approximately equal. If starting resistance is placed 1nonly two phases of the secondary winding, the currents in the threephases of said winding will be unequal, and accordingly the torque willbe low and the motor will be unable to start under load, if the load beabove a certain amount. It has been found preferable in practice tobuild induction motor controllers in which there are only two sectionsof variable starting resistance, one for each of two phases of thesecondary winding. The third phase of the secondary winding is withoutstarting resistance, and accordingly the currents in the three phases ofsaid winding are unequal when the motor circuit is first closed.

The object of my invention is to provide means whereby the resistance inthe three phases of the secondary winding will be balanced when themotor circuit is first closed, so as to provide means whereby resistancewill be placed in the three phases of the secondary winding when themotor circuit is first closed.

In accordance with my invention I use, in addition to the two sectionsof variable resistance, a third resistance so that I provide a sectionof resistance for each of the three phases of the secondary winding.These resistances are so proportioned that the current in the threephases of the secondary winding will be sufficient to start the motorunder a given load with said re sistance in circuit. I provide mycontroller with means for removing the third section of resistance fromcircuit when the other Specification of Letters Patent.

Patented Dec. S, 1914.

Serial No. 460,677.

two sections are removed from circuit. I preferably short-circuit thethird section of resistances after the other two sections have beenremoved from circuit. In practice I have worked out two controllerswhich embody my invention. I shall describe these controllers in orderto more fully explain the characteristic features of my invention. Itwill be understood, however, that my invention is susceptible of beingembodied in various other forms, and that the circuit relations andelectrical proportions of elements may be modified to suit theconditions under which the controller is to be used.

The views in said drawings are as follows:

Figure 1 is a front elevation of a controller in which the resistancevarying member moves automatically. Fig. 2 is a sectional view on theline 2-2 of Fig. 1. Fig. 3 is a sectional view taken generally on theline 33 of Fig. 1. Fig. 4c is a vertical sectional view, taken on theline 44 of Fig. 1. Fig. 5 is a diagram of the controller circuits, asapplied to a two-phase alternating current motor. Fig. 6 is adiagrammatic view of another form of controller, and its circuits, asapplied to a motor, the resistance varying element of the controllerbeing manually operated.

I shall first describe the controller which is illustrated in Figs. 1 to5. This controller is provided with a supporting frame 7 on the top ofwhich is mounted a plate 8, which forms a bearing for a shaft 9. Inpractice this shaft may carry the contacts of a reversing switch. On thefront of the supporting frame 7 are two parallel plates, or bases, 10and 11, between which is arranged a Vertically movable contact carrier12, which is slidably mounted upon a vertical rod 13. On the oppositesides of the brush carrier are mounted brackets 1d and 15, which areinsulated therefrom. These brackets carry pivoted fingers 16 and 17,which are pressed outwardly by springs 18 and 19. On the base 10 aremounted a series of vertically arranged contacts 20, and a continuousvertical contact plate 21, and on the base 11 are mounted a similarseries of vertically arranged contacts 22 and a continuous verticalcontact 23. The contact fingers 16 move over the contacts 20 through theslot.

and the plate 21, and the contact fingers 17 move over the contacts 22and the contact plate 23. The brush carrier 12 is connected to a crank24 on the shaft 9 by means of a link 25. This link is pivoted to thecontact carrier 12 and is provided with an elongated slot 26 at itsupper end. The crank 24 is provided with a crank pin 27 that protrudesThe crank 24 initially stands in an upper vertical position, asindicated in dotted lines. The brush carrier is then raised to its upperposition, as indicated in dotted lines. If it be desired to start themotor, the shaft 9 is turned so as to lower the crank in the position inwhich it is shown in full lines. The crank pin 27 will pass down theslot 26 and accordingly the link will be released from the crank,therebyleaving the brush carrier 13 free to descend. The shaft 9 maycarry suitable contacts for closing the motor circuit when said shaft isturned to operate the controller to start the motor. The brush carrieris connected to the'piston rod 28 of a dash-pot 29, which is pivotallymounted upon the frame 8. This dash-pot retards the downwardmovement ofthe contact carrler.

I shall now refer to the diagram of the circuits illustrated in Fig. 5.The induction motor 30 is provided with three brushes, 31, 32 and 33,which engage slip rings connected to the secondary winding. The pri marywinding of the motor is connected to an alternating current circuit 34,which may be a two-phase circuit as illustrated. This circuit may becontrolled by any suitable switch, as, for instance, switch contactsmounted on the shaft 9. The controller is provided with a variableresistance 35, a variable'resistance 36 and a constant resistance 37.The variable resistance 35 is connected to the contacts 20 and the brush31. The variable resistance 36 is connected to the contacts 22 and thebrush 33, and the constant resistance 37 is connected between the brush31 and the brush 33 to the contact plates 21 and 23, which areelectrically connected to each other and to the brush 32. The contactfingers 16 electrically connect the contacts 20 and the contact plate21, and the fingers 17 electrically connect the contacts 22 and thecontact plate 23. It will thus be seen that the circuit of the secondarywinding is divided into three phases, one of which extends from thebrush 3], through variable resistance 35, contacts 20, fingers 16,contact plate 21 to the brush 32. Another from the brush 33, throughvariable resistance 36, contacts 22, contact fingers 17, contact plate23 to the brush 32, and a third from a brush 31, through resistance 37to the brush 33. Accordingly in each of these phases there is a sectionof starting resistance. These sections of resistance may be equal sothat the current in each of the three phases of the secondary windingwill be equal, thereby causing the motor to develop its maximum torquefor a given current at the instant of starting. Of course, it is onlynecessary that the resistances be so proportioned that the torque, whichis developed by the motor, will be sufiicient to start the motor underthe load that is imposed thereon. As the contact fingers 16 and 17 passdownwardly over the contacts 20 and 22, the variable resistances 35 and36 are gradually removed from circuit. When these fingers reach thebottom the variable resistances 35 and 36 are entirely removed fromcircuit and the resistance 37 is completely short-circuited.

Fig. 6 illustrates another form of motor controller embodying myinvention. In this controller there is a centrally pivoted contact arm38 on which there is an operating handle 39. This arm carries twobrushes 40, 41, one at each end, which brushes sweep over contacts 42and 43 respectively. The contact arm 38 carries a brush 44 which engagesa stationary contact 45'when said arm stands in the position indicatedin dotted lines. The motor 46 has three brushes, 47, 48 and 49, whichengage slip rings connected to the secondary winding. The primarywinding of themotor may be connected to an alternating current circuit,which may be a three-phase circuit 50. A variable resistance 51 isconnected to the contacts 43, and also to the brush 47. A

second variable resistance 52 is connected to the contacts 42, and alsoto the brush 49, and a constant resistance 53 is connected to thecontact arm and also to the brush 48. As illustrated in the drawing, thecontact arm. is arranged to maintain the secondary circuit closed atalltirnes. This arrangement has been found more satisfactory inpractice, but of course the contact arm may be arranged to open thesecondary circuit if desired. When the motor is started one phase of thesecondary circuit extends from the brush 47 through conductor 54,conductor 55, to resistance 51. Another phase extends from brush 49,through conductors 56 and 57 to variable resistance 52; and stillanother from brush 48, through conductor 58 to resistance 53. Theseresistances are all connected to the contact arm. It will thus be seenthat a resistance is arranged between each of the three phases of thesecondary circuit. These resistances are so proportioned that thecurrents in the three phases are of such relative value that the torquedeveloped with the starting resistance in circuit is sufficient to startthe motor under its load. As the brushes 40 and 41 pass over thecontacts 42 and 43, respectively, the variable resistances 51 and 52 areremoved from circuit step by step.

When the contact arm reaches its final position, as indicated in dottedlines, the va-, riable resistances 51 and 52 are entirely removed fromcircuit, and the resistance 53 is short-circuited by the brush 44 andcontact :5.

While I have described herein certain electrical connections which existin the two devices that I have Worked out in practice, it will beunderstood that my invention is susceptible of being applied toalternating current motor starters in various ways without eliminatingthe features which the appended claims define.

VJhat I claim as new and desire to secure by Letters Patent is 1. In aninduction motor starter, in combination, a plurality of resistances, onefor each phase of the secondary circuit of the notor, ertain or" saidresistances being variable and another constant, and a single movablecontact member for completely remo ing all of said resistances fromcircuit through connections all made to stationary points, said movablemember bein adapted to remove said variable resistances from circuitgradually, and to short-circuit said constant resistance at apredetermined point in its movement,

In an induction motor starter, in combination, plurality of resistances,one for each phase or" the secondary circuit of the motor, certain ofresistances being variable and another constant, and a single movablecontact member for completely removing all of said resistances fromcircuit through connections all made to stationary points, aid movablemember being adapted to remove said variable resistances from circuit grdually and simultaneousl and to short-circuit said constant resistanceafter completely removing the variable resistances from circuit,

3. In an induction motor starter, in combine n, two series of contacts,variable resistances connects l to said series of contacts and connectedin different phases of the seconda y circuit or tne motor, a constantresistance for third phase of the secondary circuit of the motor, and asliding contact member arranged between said series of contacts andmovable over the same for removing said rail ole resistances fromcircuit gradually and s multaneously, said movable contact member beingadanted to short-circuit said constant resistance after com pletelyremoving said variable resistances from circuit, all circuit connectionsbetween said contact member, said resistances and the slip rings of themotor being made to stationary parts.

a. In an induction motor starter, in combination, two series ofcontacts, variable resistances connected to said series of contacts andconnected in different phases of the secondary circuit of the motor, aconstant resistance for a third phase of the secondary circuit of themotor connected between the last of said series of contacts, and asliding contact member of contacts for gradually removing said variableresistances from circuit and shortcircuiting said constant resistance,said con tact member being arranged to completely remove all of saidresistances from circuit, all connections through said sliding contactmember being made through stationary contacts.

In a controller for induction motors, in combination, two sets ofcontacts, a movable controlling member having contacts mounted thereonand arranged to engage and move over said sets of contacts, a pluralityof resistances connected to said sets of contacts, said resistancesbeing connected in different phases of the secondary circuit of themotor, said controlling member, when operated, being adapted togradually remove two of said resistances from circuit and toshort-circuit a third resistance upon completely removing the otherresistances from circuit, and a contact arranged to be continuouslyengaged by each of the contacts of said controlling member toelectrically connect the same to a common slip ring of the motor.

6. In a controller for induction motors, in combination, two parallelinsulating bases, aset of contacts carried by each of said insulatingbases, a controlling member arranged between said insulating bases andhaving contacts thereon for engaging said series of contacts, twovariable resistances, and a constant resistance connected to said seriesof contacts, said resistances being connected in different phases of thesecondary circuit of the motor and said controlling member being movableover said contacts to gradually remove said variable resistances fromcircuit and to short-circuit said constant resistance upon completelyremoving said variable resistance from circuit, and contacts on saidbases to be continuously engaged by said controlling member to directlyconnect the same with one of the slip rin gs of the motor.

i. In controller for induction motors, in combination, two insulatingsupporting bases, a series of contacts mounted on each of said bases, avariable resistance connected to each of said series of contacts, saidseries of contacts being electrically connected to different slip ringsof the motor, a constant resistance connecting said series of contacts,a controlling member having contacts engaging said series of contacts,and elongated contacts mounted on each of said bases arranged to becontinuously engaged by the contacts of said controlling member, saidelongated contacts being connected to a movable over said series thirdslip ring of the motor, said controlling scribed my name in the presenceoftWo Witmember, When operated, being adapted to nesses.

gradually remove said variebleresistances WILLIAM E. DATE from circuitand t0 short-circult said con- 7 stant resistance upon completelyremoving 'lVitnesses: said Variable resistances from circuit. F. G.JoU'rRAs, In Witness whereof, I have hereunto sub- 'R. E. LUDWICK.

Copies .0! this patent may be obtained for five cents each, byaddressing the Commissioner ,of Eatenta,

Washington, D. G. V

